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Slow Medicine: Holding Firm on Our Approach to Colon Cancer Screening

— We favor occult blood testing rather than invasive tests

Ƶ MedicalToday

Last week the American Cancer Society (ACS) released its . The big news: the leading cancer society now recommends routine screening beginning at age 45 through the age of 75. Prior ACS guidelines from 2008, as well as other colorectal cancer screening recommendations, had recommended screening starting at age 50.

Notably, the downshift in the target age range for screening was not triggered by new clinical trial data supporting the change, but rather by modeling based on a rising prevalence of colorectal cancer among U.S. adults in their 40s. The new guidelines do indicate that screening in the 45-49 age bracket is a "qualified" recommendation, whereas screening for those 50 and above is a strong recommendation. However, the guidelines do not recommend counseling patients that there are a variety of expert opinions regarding when to initiate screening, and that beginning screening before age 50 has known risks but largely theoretical benefits.

In another change from the 2008 guidelines, the new recommendations now encourage clinicians to discuss multiple screening modalities with patients, including:

  • fecal immunochemical test annually
  • high‐sensitivity, guaiac‐based fecal occult blood test annually
  • multi-target stool DNA test every 3 years
  • colonoscopy every 10 years
  • computed tomography colonography every 5 years
  • flexible sigmoidoscopy every 5 years

Previous guidelines had favored invasive colon cancer screening strategies, such as colonoscopy, as the preferred approach. The American Gastroenterology Society similarly recommends colonoscopy as the preferred screening approach, whereas the United States Preventive Services Task Force with either "fecal occult blood testing, sigmoidoscopy, or colonoscopy" for adults ages 50 to 75.

The new recommendations provide us with an opportunity to review our Slow Medicine approach to colorectal cancer screening.

The Slow Medicine Approach

As we have previously written, we favor occult blood testing for colon cancer screening rather than invasive tests like colonoscopy (see also Rita Redberg's making the case for this approach). Put simply, occult blood testing is the safest, simplest available screening strategy. According to a published in Gastroenterology, unplanned hospitalizations occur following approximately 16 out of every 1,000 colonoscopies. Moreover, a found that sigmoidoscopy reduces the risk of colon cancer mortality from about 8 per 1,000 to 6 per 1,000 over 10 years (number needed to screen ~500).

Assuming that the benefits of sigmoidoscopy are comparable to those of colonoscopy, this means that you are about eight times more likely to end up in the hospital within a week of your screening colonoscopy than you are to be saved from colon cancer death over 10 years. Of the major screening guidelines, the only set constant with our approach is the , which recommend stool tests ever 2 years or sigmoidoscopy every 10 years.

As for the appropriate age to begin screening, we support the age bracket of 50 to 75 because this is the age group for which the data are most compelling. In fact, the Canadian guidelines highlight that the evidence for screening is strongest among those ages 60 to 74 and less so for those 50 to 60. Although we appreciate the rising incidence of colorectal cancer among younger individuals, we do not believe it would be justified to shift the screening age until rigorous evidence demonstrates the benefits of screening in younger populations; there are too many potential unintended consequences.

In summary, and at least until new data emerge, we believe occult blood testing should be the default method for colon cancer screening, with sigmoidoscopy and colonoscopy reserved for those who request it. Fecal tests are certainly the safest method. This strategy has the added benefit of providing more availability for colonoscopy among patients with a positive fecal occult test.

And until rigorous research demonstrates a clear and consistent benefit among younger populations, we think it is prudent to focus our screening efforts on those ages 50 to 75.

"Updates in Slow Medicine" applies the latest medical research to support a thoughtful approach to clinical care. It is produced by , of Harvard Medical School, and , of the Keck School of Medicine at the University of Southern California. To learn more, visit the .